In a typical cellular radio system, wireless user equipments (UEs) communicate via a radio access network to one or more core networks. The wireless user equipments (or simply user equipments) can be mobile stations, mobile terminals, or wireless terminals/stations such as mobile telephones (“cellular” telephones) and laptops with mobile termination, and thus can be, for example, portable, pocket, hand-held, computer-included, or car-mounted mobile devices which communicate voice and/or data with radio access network. Alternatively, the wireless user equipments can be fixed wireless devices, e.g., fixed cellular devices/terminals which are part of a wireless local loop or the like.
The radio access network covers a geographical area which is divided into cell areas, with each cell area being served by a radio base station (RBS) (also known as a base station, NodeB, or Node_B, for example). A cell is a geographical area where radio coverage is provided by the radio base station equipment at a radio base station site. Each cell is identified by a unique identity, which is broadcast as system information in the cell. The radio base stations communicate over the air interface with the user equipments within the range of the radio base stations. In the radio access network, several radio base stations are typically connected (e.g., by landlines or microwave) to a radio network controller (RNC). The radio network controller, also sometimes referred to as a base station controller (BSC), supervises and coordinates various activities of the radio base stations connected to the radio network controller. The radio network controllers are typically connected to one or more core networks. The core network has two service domains, with an radio network controller having an interface to both of these domains.
One example of the radio access network is the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN). The UMTS is a third generation system which in some respects builds upon the radio access technology known as Global System for Mobile communications (GSM) developed in Europe. UTRAN is essentially a radio access network providing wideband code division multiple access (WCDMA) to the user equipments. The Third Generation Partnership Project (3GPP) has undertaken to evolve further the UTRAN and GSM-based radio access network technologies.
There are several interfaces of interest in the UTRAN. The interface between the radio network controllers and the core network(s) is termed the “Iu” interface. The interface between a radio network controller and its radio base stations is termed the “Iub” interface. The interface between the user equipments and the radio base stations is known as the “air interface”, the “radio interface” or the “Uu interface”. In some instances, a connection involves both a Source or Serving radio network controller (SRNC) and a target or drift radio network controller (DRNC), with the SRNC controlling the connection but with one or more diversity legs of the connection being handled by the DRNC. An Inter-RNC transport link can be utilized for the transport of control and data signals between the SRNC and the DRNC, and can be either a direct link or a logical link. An interface between radio network controllers (e.g., between a SRNC and a DRNC) is termed the “Iur” interface.
The radio network controller controls the UTRAN. In fulfilling its control role, the radio network controller manages resources of the UTRAN. Such resources managed by the radio network controller include (among others) the downlink (DL) power transmitted by the radio base stations, the uplink (UL) interference perceived by the radio base stations, and the hardware situated at the radio base stations.
In some 3GPP systems (e.g., either WCDMA or TD-SCDMA), the radio network controller will require the radio base station to perform some measurements and report the measurement results back to the radio network controller through the Iub interface. The radio network controller will likely initiate and control the reporting process, and thus controls such information/parameters as measurement types, the reporting periods, and so on. Based on the measurement results received from the radio base station, the radio network controller can better evaluate handover, resource allocation or other functions.
There are many potential types of measurements and a potentially large range for the reporting periods. Normally, it is advantageous for the radio network controller to receive measurement results as frequently as possible to improve evaluation accuracy and response in time. However, different types of radio base stations, especially from different vendors, have differing processing power for the Iub signaling, and thus have differing measurement report capabilities. So an improper setting of measurement control parameters by a radio network controller could cause a particular radio base station to be overloaded by the reporting requirements to the radio network controller. When the radio base station may be overwhelmed by the radio network controller measurement reporting requirements, activities (such as an interoperability test (IOT)) between the radio network controller and the radio base station will be very difficult.
Moreover, in view of its own internal structure and/or current processing load, it is possible that the radio network controller may have its own limitation as to how many measurements it can handle, e.g., how many measurement reports it can effectively receive from the radio base stations. Thus, it is possible that an improper setting of measurement control parameters by the radio network controller could cause the radio network controller itself to be overloaded by the reporting requirement which it imposes on the radio base stations for reporting to the radio network controller.